Doesn't pgstat_report_wal() handle the argument "force" incorrectly

From: Ryoga Yoshida <bt23yoshidar(at)oss(dot)nttdata(dot)com>
To: pgsql-hackers(at)lists(dot)postgresql(dot)org
Subject: Doesn't pgstat_report_wal() handle the argument "force" incorrectly
Date: 2023-09-22 04:58:37
Message-ID: f87a4d7be70530606b864fd1df91718c@oss.nttdata.com
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Hi,

pgstat_report_wal() calls pgstat_flush_wal() and pgstat_flush_io(). When
calling them, pgstat_report_wal() specifies its argument "force" as the
argument of them, as follows. But according to the code of
pgstat_flush_wal() and pgstat_flush_io(), their argument is "nowait" and
its meaning seems the opposite of "force". This means that, even when
checkpointer etc calls pgstat_report_wal() with force=true to forcibly
flush the statistics, pgstat_flush_wal() and pgstat_flush_io() skip
flushing the statistics if they fail to acquire the lock immediately
because they are called with nowait=true. This seems unexpected behavior
and a bug.
void
pgstat_report_wal(bool force)
{
pgstat_flush_wal(force);

pgstat_flush_io(force);
}

BTW, pgstat_report_stat() treats "nowait" and "force" as the opposite
one, as follows.
/* don't wait for lock acquisition when !force */
nowait = !force;

Ryoga Yoshida

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